Process of preparing filaments for incandescent lamps.



Patented Apr. 22, 1913.

. gt} INVENTOR AT'TORNEY W. G. HOUSKEEPER.

PROCESS OF PREPARING FILAMENTS FOR INGANDESGENT LAMPS.

APPLICATION FILED AUG. 6, 1910. RENEWED SEPT. 13, 1912.

WITNESSES:

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UNITED STATES PATENT OFFICE. wIL IIAH-G, H OUSKI EPEB, OI PHILADELPEIAQPENNSYLVANIA, ASSIGNOR T0 WEST- INGI H OUSE LAIP COMPANY, ACORPORATION OF PENNSYLVANTI A.

PROCESS OF PREPARING FILAMENTS FOR INCA NDESCENT LAM-PS.

ama... of mm; rum.

Patented Apr. 22, 1913.

Application fled August 8, 1910, Sci-1:180. 575,987. lenewed September18, 1912. Serial No. 720,278.

ment in Processes of Preparing Filaments for Incandescent Lamps, ofwhich the following is a specification. Y

My invention. relates to processes of treating filamentary material forthe purpose of rendering the same suitable for filaments of electricincandescent lamps, and it has for its object to provide a processwhereby alternating current may be employed instead of direct currentfor the purpose of heating the filaments and sintering its particlestogether.

In an application, Serial No. 486,925, filed March 31, 1909, by Harry D.Madden and myself, and assigned to the Westinghouse Lam Company, is setforth a process of treating filamentary material'which consists inapplying different amounts of electric current to different portionsthereof, the object of such treatment being to gradually heat thefilament in order to carbonize the binder for the main ingredients ofthe filamentary material, and to thereafter sinter together theparticles of said ingredients.

It has been found that, if single-phase alternating current is appliedto the fila-- mentary material, in practising this process, the filamentis alternately heated and cooled,

and, consequently, it alternately expands and contracts, with the resultthat it is frequently broken during treatment. According to the presentinvention, I propose to so apply polvphase currents to the differentsections of the filament that the total length of the portion of the,filament under treatment will remain substantially uniform, in orderthat there may be substantially no greater strain upon the filament thanwhen direct current is employed in practising the process.

The single figure of the accompanying drawing illustrates,diagrammatically, suitable apparatus for practising my invention.

As set forth in the'above-mentioned application, the untreatedfilamentary material 1, after leaving the press2, passes through aseries of terminal devices, 3, 4, 5, 6, 7, 8

and 9, that preferably consist of apertured lates or members, theportions of which adacent to the apertures therein are amalgamated, andacross the apertures in which extend bodies of mercury '10, that aremaintamed in the apertures by capillar and surface. tension, and the suraces of which are preferably of-concave form. The terminal devices 3, 4and 5 are connected, in series with lamps 11, 12 and 13, respectively,or with other suitable current-regulating devices, to one terminal of atwo-phase source 14, the other terminal of the same phase of which isconnected to the terminal device 6, an auto-transformer 15, or othersuitable current regulating device, being rovided for adjusting thetotal amount 0 current supplied to the filament through the termicurrentsupplied to the filament through the terminal devices 6 to 9, inclusive.While certain kinds of filaments may be treated in air, as shown, othersare preferably treated in a non-oxidizing atmosphere, the process beingotherwise the same.

As the currents traversing the portions of action' the filamentarymaterial above and below the terminal device 6 are different. in phase,the one portion will behottest when the other is coolest. The result isthat when the upper portion is contracting, the lower portion isexpanding, and vice versa, and the total length ofvthe portion of thefilament under treatment remains substantially uniform. There is,consequently, little or no strain upon the filament resulting from itsexpansion and contraction, and but little liability of its breakage.

Of course, the invention is not limited to the use of two-phasecurrents, but the circuits may obviously 'be arranged so that three orany other suitable number of phases or current may be applied to thefilament.

I claim as my invention:

1. The method of treating filamentary material which consists insimultaneously passing differently phased electric currents throughdiflerent portions thereof.

material which consists in simultaneously passing. different amounts ofelectric current througi different portions thereof, thecurrenttraversing certain portions of the filamentary material being-ofa different phase from that traversing other portions thereof.

. 3. Apparatus of the character described,

, comprising a-fplurality of alined terminal members, a source ofpolyphase alternating currents and connections between the said sourceand the said terminal members whereby a conductor engaging the saidterminal members have diflerently phased currents applied to differentportions thereof.

4. Apparatus of the character described, comprising a plurality ofalined terminal members, a source of polyphase alternating members willhave vcurrents and connections between the said source and thesaidterminal members whereby a conductor engaging the said terminal'iflerently phased cur.-

rents applied to different portions thereof,

and means includedin said connections whereby different amounts ofcurrent are .WILLIAM G. HOUSKEEPER.

Witnesses CHARLES KELLY, C. W. YOUNGHOLM.

